Neuromonitoring of the external branch of the superior laryngeal nerve during minimally invasive thyroid surgery under local anesthesia: a prospective study of 10 patients.

OBJECTIVES/HYPOTHESIS: Avoiding alterations of the voice is a challenge in thyroid surgery. Identification and preservation of the external branch of the superior laryngeal nerve (EBSLN) is paramount for normal vocal function preservation after thyroidectomy. Conventional nerve monitoring requires a general anesthesia and placement of a special endotracheal tube equipped with electrodes to evoke the laryngeal nerves. This study aims to assess feasibility and efficacy of a novel technique of neuromonitoring of the EBSLN under local anesthesia during minimally invasive thyroidectomy. STUDY DESIGN; PROSPECTIVE STUDY: This study is a prospective trial to evaluate the efficacy of nerve monitoring of the EBSLN during minimally invasive thyroidectomy under local anesthesia. Patient self-assessment of changes in perceived voice severity prior to and 3 weeks after surgery was assessed with the Voice Handicap Index-10 (VHI-10).
RESULTS: Thyroidectomy was successfully completed under local anesthesia in all cases. The recurrent laryngeal nerve(s) was identified and preserved in each patient as demonstrated by normal perioperative transnasal flexible laryngoscopy. A total of 15 EBSLNs were at risk, but only 8 EBSLNs (53%) were definitively identified. Neuromonitoring demonstrated preservation of the EBSLN in 100% of cases. The analysis of the results of the VHI-10 questionnaire before and 3 weeks after surgery indicated no significant change in patients' perception of voice severity.
CONCLUSION: Monitoring of the EBSLN during thyroidectomy under local anesthesia is a feasible alternative to conventional nerve monitoring under general anesthesia. This technique may be useful for the preservation of voice quality during a minimally invasive thyroidectomy under local anesthesia.